Method of producing iridescent coatings

ABSTRACT

A method of producing an iridescent reflecting surface on an object is presented. Flakes of dry non metallic reflecting material such as cholesteric liquid crystal (CLC) material are applied to the surface so that the flakes are parallel with the surface and bound with a binder to the surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] This document describes a technology for painting and imageprinting that utilizes a simple system with multiple colorants and asingle printing head through which the image is printed by a transparentink or binder. The primary area of interest involves dry pigments oflarger molecular weight colorants, such as cholesteric liquid crystal(CLC) pigments, and their diverse applications in modern printing andpainting. In addition, new techniques can be easily expanded to servemore functions, such as 3-D stereoscopic image capability.

[0003] 2. Brief Description of the Literature

[0004] Broadband reflecting polarizers were introduced in applicationSer. No. 08/550,022 (now U.S. Pat. No. 5,691,789) entitled “Single LayerReflective Super Broadband Circular Polarizer and Method of FabricationTherefore” by Sadeg M. Faris and Le Li which was filed Oct. 30, 1995.Such broadband polarizers are made by producing a single layer havingcholesteric liquid crystal order where the pitch of the liquid crystalorder varies in a non linear fashion across the layer.

[0005] General references on polymer dispersed liquid crystals may befound in detail in “Polymer Dispersed Liquid crystal displays”, by J. W.Doane, a chapter in “Liquid Crystals”, Ed. B. Bahadur, World ScientificPublishing, Singapore, and “CLC/polymer dispersion for haze-free lightshutters, by D. Yang et al. Appl. Phys. Lett. 60, 3102 (1992).

[0006] Since the early attempt of utilizing cholesteric film as opticalfilters and the effort on polymer encapsulated nematic liquid crystalsfor display, much attention has been focused on trying to bringpolymeric liquid crystals and cholesteric liquid crystals together tomake devices for light control application. (See, for example J. Adams,W. Hass, J. Dailey, Journal of Applied Physics, 1971, and J. L.Fergason, Society-for Information Display Digest, 1985.). The aboveidentified US patents and other references are hereby incorporated byreference.

Related cases

[0007] The following applications are related to the present invention:Application Ser. No. 9/093,017 filed Jun. 5, 1998; application Ser. No.09/093,006 filed Jun. 5, 1998; application Ser. No. 09/039,303 filedMar. 14, 1998; application Ser. No. 09/039,297 filed Mar. 14, 1998;application Ser. No. 08/891877 filed Jul. 9, 1997 entitled “ReflectiveFilm Material Having Symnmnetrical Reflection Characteristics and Methodand Apparatus for Making the Same”, by Le Li and Sadeg Faris applicationSer. No. 08/739467 filed Oct. 29, 1996 entitled “Circularly PolarizingReflective Material Having Super Broad-Band Reflecting & TransmissionCharacteristics & Method of Fabricating & Using Same in Diverseapplications” by Sadeg M. Faris, Le Li, and Yingqiu Jiang Jiang.application Ser. No. 08/890320 filed Jul. 9, 1997 entitled “ColoringMedia Having Improved Brightness and Color Characteristics” by Sadeg M.Faris and Le Li application Ser. No. 08/805,603 entitled“Electro-optical glazing structures having total-reflection andtransparent modes of operation for use in dynamical control ofelectromagnetic radiation” by Sadeg M. Faris and Le Li, filed Feb. 26,1997, which is a continuation-in-part of: copending application Ser. No.08/739,467 entitled “Super Broadband Reflective Circularly PolarizingMaterial And Method Of Fabricating And Using Same In Diverseapplications”, by Sadeg M. Faris and Le Li filed Oct. 29, 1996, which isa is a Continuation-in-Part of copending application Ser. No. 08/550,022(Now U.S. Pat. No. 5,691,789) entitled “Single Layer Reflective SuperBroadband Circular Polarizer and Method of Fabrication Therefore” bySadeg M. Faris and Le Li filed Oct. 30, 1995; copending application Ser.No. 08/787,282 entitled “Cholesteric Liquid Crystal Inks” by Sadeg M.Faris filed Jan. 24, 1997, which is a Continuation of application Ser.No. 08/265,949 filed Jun. 2, 1994, which is a Divisional of applicationSer. No. 07/798,881 entitled “Cholesteric Liquid Crystal Inks” by SadegM. Faris filed Nov. 27, 1991, now U.S. Pat. No. 5,364,557; copendingapplication Ser. No. 08/715,314 entitled “High-Brightness Color LiquidCrystal Display Panel Employing Systemic Light Recycling And Methods AndApparatus For Manufacturing The Same” by Sadeg Faris filed Sep. 16,1996; copending application Ser. No. 08/743,293 entitled “Liquid CrystalFilm Structures With Phase-Retardation Surface Regions Fonned ThereinAnd Methods Of Fabricating The Same” by Sadeg Faris filed Nov. 4, 1996.Each of the above identified Application s and patents are commonlyassigned to the assignee of the present invention, and are incorporatedherein by reference in their entirety.

INTRODUCTION

[0008] In modern society, information exchange plays an important role.Efficient methods to convey information rely on high-qualitycommunication devices. Among them, printing and painting devices arebecoming more and more important. Currently, inkjet, bubble jet, andlaser printing, along with off-set, flexo press, and screen printing areuniversally used. All of these printing techniques possess a commonfeature. In order to perform color printing, multiple nozzles or screensmust be used for cyan, magenta, yellow and black colorants. This forcesthe printing system to become mechanically complex and limits the systemfrom being able to be expanded to serve multiple functions such as thecase of 3-D printing. In addition, since the printing nozzles andscreens have a very fine apertures, they can't handle those colorantswith relatively larger pigment particles.

[0009] Furthermore, it has been known that CLC can be used as a colorantfor painting and printing because of their excellent spectralcharacteristics and wide color range properties. However, specialtechniques must be employed in order to use CLC. Special surfacetreatments and curing methods are all necessary to print and dry CLCfilms. As a result, CLC has never been practically used in real artworkor other applications. However, the present invention of the new CLC inkbased on CLC pigment solves all these problems at once. No specialsurface treatment and curing equipment is required to dry and/or curethe colorant. Another benefit is the capability of generating colorful3-D stereoscopic images since the CLC ink reflects polarized light.

OBJECTS OF THE PRESENT INVENTION

[0010] One objective of this invention is to improve today's printingtechnologies. The inventors of the present invention have developed anew printing technology that offers a simple system configuration,greater flexibility, improved printing quality, and enhancedfunctionality. The new technique is termed Dry Printing Technology (DPT)by its working principle. It uses only one printing head and printsimages with an invisible ink. It can handle, in principle, all kinds ofcolorants, even colorants with larger pigments so that it removes thepigment size constraint in ink jet nozzle printing. By adopting a newprinting head combined with CLC pigments, dry printing offers enhancedimage quality. Finally, DPT can be easily expanded to print a colorfulpicture in 3-D with the CLC pigments.

[0011] Another objective is the application of the invented printingtechnique using a newly developed, novel colorant to achieve uniquedisplay effects that usual technologies do not possess. The ink is madefrom CLC pigments mixed into a suitable optically clear carrier.

[0012] Yet another objective is to give printing devices moreflexibility and enhance their functionality.

[0013] Yet another objective is to achieve a special visual effect ofobjects which appear to have different colors depending on the viewingangle.

[0014] Yet another objective is to create 3-D stereoscopic images infull color at any size.

[0015] Yet another objective is to provide security printing

[0016] Yet another objective is to provide unique cosmetic effects.

[0017] Other objects, advantages, and novel features df the presentinvention will become apparent from the following detailed descriptionof the invention when considering in conjunction with the accompanyingdrawings.

SUMMARY OF THE PRESENT INVENTION

[0018] The present invention provides a method of using flat flakes ofnon metallic reflecting pigment by applying the flakes to a surface andensuring that the flakes lie substantially parallel to the surface. Abinder material may first be adhered to the surface in a pattern oruniformly. The flakes are applied to the surface, and stick where thebinder has been prepared. The flakes are applied so that they lieparallel to the surface, or the flakes are applied, then rolled orbuffed to align them parallel to the surface. If the flakes are CLCflakes, multilayer polymer flakes, or multilayer inorganic materialflakes, an iridescent filmwhich changes color with viewing angle may beproduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 shows a prior art “paint layer”.

[0020]FIG. 2 shows a pigment material is in the form of flakes.

[0021]FIG. 3.shows a flow chart of the apparatus of the invention.

[0022]FIG. 4 shows an embodiment of the invention.

[0023]FIG. 5 shows an embodiment of the invention.

[0024]FIG. 6 shows an alternative embodiment of the invention

[0025]FIG. 7 is a flow chart of the method of the invention.

[0026]FIG. 8 is a flow chart of a preferred embodiment of the invention.

[0027]FIG. 9 shows a flow chart of a preferred embodiment of theinvention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0028] The present invention, termed “Dry Printing Technology” (DPT),enables many new applications to surface. The central part of the newtechnology is to print an image with an optically clear ink through asingle printing head followed by an applying of CLC pigments.

[0029]FIG. 1 shows an object 10 having a surface 12 covered with a priorart “paint layer” 14. The paint layer 14 generally comprises pigmentparticles 16 dispersed in a binder material 18.

[0030]FIG. 2 shows a paint layer like FIG. 1 where the pigment materialis in the form of flakes 20. The flakes 20 are shown randomly dispersedin the binder material 18. For reflective non metallic pigment particleslike CLC flakes, multilayer polymer material flakes, or inorganicmultilayer material flakes which have reflectivity by virtue of theinterference effect of light reflection from a spatially varying indexof refraction, the angle of viewing is critical, and no coherent effectis gained when the eye sees a large collection of pigment particles atmay different angles. The use of CLC flakes is described in detail incopending application Ser. No. 08/787,282 entitled “Cholesteric LiquidCrystal Inks” by Sadeg M. Faris filed Jan. 24, 1997, and in applicationSer. No. 07/798,881 entitled “Cholesteric Liquid Crystal Inks” by SadegM. Faris filed Nov. 27, 1991, now U.S. Pat. No. 5,364,557. Multilayerpolymer reflecting material in sheet form and flake form is well known,as are multilayer inorganic coating for reflective and antireflectivecoatings optical substrates. The CLC flakes can be manufactured so thatthe pitch of the helix of the CLC molecules is non-linear, as detailedin the above mentioned patent applications, and so the flakes are broadband reflectors. In a similar way, the pitch of the polymer andinorganic multilayer films can be changed throughout the films toproduce broad band reflecting flakes.

[0031]FIG. 3. shows a flow chart of apparatus of the the invention. TheImage Generator 30, which may be a computer, photograph, silk screen,image plate, or manual drawing, provides the information to be printed.The image is transmitted to a means for applying a binder material, orthe Binder Material Applicator module 32, which is one of thefundamental components of the Dry Printing technology. Pictures orimages are printed in the most preferred embodiment using a transparentink or binder material rather than a conventional colorant. Transparentbinder material allows the printing process to be repeated many times tobuild layers of different color pigment material. An alternativeembodiment allows use of a light absorbing binder material to bind lightreflective pigment particles. Light which is not reflected from thepigment particles passes through the pigment particles and is absorbedin the light absorbing binder so that only the color reflected from thepigment particles may be seen.

[0032] Equally important, the means for transparent ink or binderprinting may employ techniques from most printing technologies. Forexample, ink-jet, bubble jet, and laser printing, as well as flexopress, off-set, gravure printing and silk screen printing may serve asthe methods and apparatus for transparent ink printing in module 32However, minor changes and/or modifications might be required to thepre-existing printing systems to account for transparent ink printingconditions such as printing heat or environment. Printing with a binderor invisible ink allows the use of pigment particles of any size, sincethe pigment particles do not have to pass through the nozzles, screens,or other devices used to print normally. While particles and flakes ofless than 40 or 50 microns diameter give good resolution and passthrough most printers without clogging, larger pigments particles whichmay be used for special effects are difficult to use.

[0033] Dry Pigment application by module 34 is another central part ofthe unique dry printing process. Before the invisible ink patternprovided by module 32 is completely cured, dry pigments are applied bymodule 34 to the ink surface to cover the printed area. The dry pigmentsadhere to the patterned surface in the pattern printed by the means forapplying binder material 32. The dry pigments may be removed from thesurface which has no binder material by shaking, vacuuming, or otherstandard way of removing dry powder from a surface. The dry pigmentsare, in the most preferred embodiments, either commercially available,conventional absorptive pigments or the novel non metallic reflectingCLC pigments or other iridescent flakes. Flakes of other absorptivepigment materials are also anticipated by the inventors. The CLC flakesand other multilayer flakes give spectacular reflective layer effects,and may also be used in transmission, for they transmit those colorswhich they do not reflect. Other dry pigments are also anticipated bythe inventors. Dry pigment applicator 34 may contain multiple colorants,such as reflective red, green, blue, and white (RGBW) pigments, whichare applied onto a black surface; or, absorptive cyan, magenta, yellow,and black (CMYB) pigments that are applied onto a white surface.

[0034] Furthermore, the applicator 34 may have another mechanism 35 tomechanically align pigments, which is of great importance in the usageof CLC pigments or other pigments which are in the form of flakes. As aresult, all the dry flake pigments are uniformly oriented and layered onthe flat surface. The output device 36 allows for the Visualization ofthe colorful image. The output device 36 may also include a means forreturning the object being printed to the binder material applicator 32to apply another pattern for another color pigment or for anotherpolarization reflecting pigment. The output device 36 may also have adevice for applying a protective coating to protect the binder layer andpigment layer or layers.

[0035]FIG. 3 may also be used to describe process whereby no image isprinted in transparent ink printing module 32, but a uniform coating ofbinder material is laid on a surface, such as the surface of anautomobile, and dry pigments are applied to the surface by device 34 toproduce striking effects using CLC pigment flakes. The CLC pigmentflakes may be composed of two layers, a left handed polarization layerand a right handed polarization layer, whereby light incident on theflake is 100% reflected. Such flakes may be produced, for example, bycoating a layer of alignment material such as polyimide on to a flatsurface, buffing the polymide surface to produce an aligned surfacelayer, deposition of a first polarization CLC coating on the alignedsurface layer to produce a reflector of light of a first polarization,and immediately depositing a layer of a second polarization CLC materialon to the first polarization CLC coating. The top surface of the firstpolarization CLC coating is itself aligned and will force the secondpolarization CLC coating to align and act as a reflector for light ofthe second polarization. Thereafter the first polarization and secondpolarization coatings are removed in the form of flakes which arereflective of both polarizations.

[0036]FIG. 3 may also be used to describe a process whereby a uniformcoating of binder material is laid on a surface in transparent inkprinting module 32, and dry pigments are applied to the surface in apattern in module 34. The pattern is then fixed by fusing or otherwisecuring the binder material.

[0037]FIG. 4 shows an object 10 which has a binder coating 40 applied tothe surface 12 of the object. Pigment flakes 20 have been applied to thesurface of the binder coating 40, and are being rolled or buffed by theobject 42 so that the pigment flakes 20 lie substantially parallel withthe surface 12 of the object 10.

[0038]FIG. 5 shows the result of the preparation of FIG. 4 when anotherlayer 50 of material is applied over the flakes 20 and binder material40 as a protective layer. It is an embodiment of the invention to haveeither the binder material 40 or the Material of protective layer 50 orboth have an index of refraction equal to the mean index of refractionof the flakes 20. In this way, light will not scatter from the edges ofthe flakes 20 and wash out the iridescent effects gained by theinterference of light within the flakes 20.

[0039]FIG. 6 shows an alternative embodiment of the invention where theflakes 20 are electrically charged and caused to lay down on the surfaceof the binder material by an electrical field at the surface of thebinder material 40. If the dimensions of flakes 20 are sufficientlylarge compared to the thickness of flakes 20, the flakes will lie downsubstantially parallel to the surface 12. Such techniques allow the useof flakes 20 with large length and width dimensions compared with thethickness of the flakes 20. A brilliant sparkling effect is created whenflakes 20 are larger than 100 microns. Even more preferred are flakeswith mean transverse dimensions greater than 150 microns.

[0040]FIG. 7 is a flow chart of the method of the invention. Step 70involves applying a binder material to the surface of the object. Thebinder material may be patterned or unpatterned. In a preferredembodiment, the binder material is applied as a liquid in a pattern, andthe dry pigment material is applied in step 74 directly to the patternedbinder material while the binder material is wet. The dry pigment sticksto the wet binder material, and may be shaken off or otherwise removedfrom the surface of the object where no binder material has beenapplied. In a preferred embodiment, the pigment material is rolled orbuffed in step 76 to align the pigment material flakes parallel to thesurface of the object. In another preferred embodiment, the bindermaterial may be dry, and the surface prepared in step 72 in a pattern byapplying a solvent material such as water to the surface in a pattern sothat the pigment material sticks in a pattern. In another embodiment,the surface of the object may be coated with a binder material that maybe fused, like a wax. The binder material is fused in a pattern and thepigment material applied so that the pigment material sticks to thefused binder material In another embodiment, the binder material may becoated with dry pigment first, and the binder material fused or coatedwith a solvent to “fix” the pigment material in a pattern. It isgenerally preferred that the dry pigment material is not fused in thefixing operation of fusing the binder material. A final step involvesapplying a protective coating in step 78. The protective coating may betransparent, or may be colored for special effects. The index ofrefraction of the protective coating 78 may match the mean index ofrefraction of the flakes in order to cut down scattering from the edgesof the flakes. The index of refraction of the binder material may alsomatch the mean index of refraction of the flakes for the same reason.

[0041]FIG. 8 is a flow chart of a preferred embodiment of the inventionwhere a binder material is coated on the surface of an object in step80, and then flakes of pigment are deposited in a pattern. Such flakescan be deposited by electrostatic means as in a xerographic photocopier,for example. After the flakes are deposited in step 82, the surface ofthe object may be worked by rolling or buffing to align the flakesparallel to the surface as shown in step 84. The flakes may be firmlyadhered to the surface in step 86 by treating the surface with a solventor by fusing the binder material. Once again, the surface may beprotected by applying a protective layer in step 88.

[0042]FIG. 9 shows a flow chart of a preferred embodiment of theinvention, in that the steps of the previous embodiments discussed abovemay be repeated in steps 90, 92, 94, 96 and 99 for different colors ofpigments or different polarization reflection characteristics ofpigments. The decision step 98 sends the system back around the loopuntil the required multiple color or multiple dimension image iscomplete.

[0043] The following is a detailed description encompassing specificapplications of transparent printing as well as pigment applicationutilized in present printing technology processes. RBGW colorants willbe used in the discussion, however, cyan, magenta, yellow and black(CMYB) colorants are also applicable.

[0044] 1. DPT via Printing Screen

[0045] In this technology, the printing screen carries the image to beprinted. One screen is needed for each one color printing. To printcolorful image, four screens are needed that represent red, green, blue,and white (RGBW) colorants. For printing in 3-D using RGBW CLCcolorants, eight screens are then needed. The first four (RGBW) are forthe right image perspective, and the other four (RGBW) for the leftimage perspective. Typically, reflective pigments are applied to a blackbackground which absorbs all the light which is not reflected, whileabsorptive pigments are applied to a white background which reflects alllight which is not absorbed. To print single color pictures, theoptically clear ink image is printed onto the substrate through thescreen. Before the ink has completely dried, CLC pigments are spreadonto the surface of the carrier followed by a mechanical alignmentbrush. If necessary, a top coating will be applied to protect the image.

[0046] To print full color image, RGBW is printed in an arbitrarysequence. For example, the red image is printed in transparent ink ontothe carrier through the “red color” screen. Then red CLC pigments areapplied. Next, after the red image has completely dried, the green imageis printed using the appropriate image screen and green CLC pigments areapplied. The same procedure is then applied to printing the blue andwhite images. To print colorful image in three dimensions, the aboveprocedure is repeated for both left and right image perspectives withleft and right handed RGBW CLC pigments.

[0047] 2. DPT via Painting Brush/Spray

[0048] This technology is particularly important in, but not limited to,painting an object such as an automobile. First of all, a carrier (suchas a primer etc.) is painted onto an object via sprayer or brush. Beforethe carrier dries, the CLC pigments are spread onto the object followedby mechanical brushing to orient the CLC pigments. Finally, a protectivecoating is applied over the CLC paint if necessary.

[0049] This method can also be used to paint colorful pictures in 3-D inlarge size. The procedure is very similar to the screen printingtechnology described above.

[0050] 3. DPT via Xerox/Laser Printer

[0051] The existing photo xerography and laser printing technologies canbe modified to use the CLC pigments as their colorants. In theseprocesses, the black carbon toner is replaced with CLC pigments. Asexperimentally proven, CLC pigments can be easily charged via staticelectric field, which is a necessary condition for Xerox and laserprinting. In contrast to the xerography process, the pigment particlesare not fused to the uncoated paper, but the non-fusible pigmentparticles which are deposited on a binder coated paper are fixed to thepaper by fusing, for example, the binder material. The sheet beingprinted is stable after one color is printed, and may be sent throughthe same or another xerography process to add other colors or otherpolarization CLC flakes to the partially printed sheet.

[0052] 4. DPT via Ink Jet Printer/Bubble Jet Printer

[0053] The same principal is applied in this case as in thescreen-printing. The image is printed using the clear carrier throughthe ink jet or bubble jet printer. Then, the CLC pigments are appliedbefore the carrier is dried followed by a mechanical brushing foralignment. The same procedure as with screen-printing is applied forprinting full color pictures as well as color 3-D images.

[0054] 5. DPT via Wax Printer

[0055] First, the wax binder layer, which may be coated on a thin filmor on a paper sheet, is thermally melted. Then, the CLC pigments aresprayed onto the “wet” wax surface followed by a mechanical brush beforethe wax solidifies. In an alternative embodiment, the CLC pigments aredeposited in a pattern and aligned on wax which is coated onto a thinfilm. RGB and White CLC wax foils are prepared in a similar way. Theimage may be transferred from a foil to paper by pressing the foil andpaper together and heating to transfer the wax and the pigment from thefoil to the paper surface. Therefore, an image is printed. If RGB andwhite wax foils are made with left and right handed CLC pigmentsseparately, then colorful 3-D printing will be achieved via thistechnology.

[0056] 6. DPT via Off-set Printer and Gravure Printer

[0057] A similar technique used for screen printing can be used inoff-set printing technology as well. Image is first printed with theclear carrier. Then CLC pigments of one color are sprayed and brushedbefore the carrier is completely dried. Also, the 3-D picture can beprinted with the left and right handed CLC pigments.

[0058] 7. DPT on Pre-treated Substrates

[0059] This method applies to all the printing technologies mentionedabove. Rather than printing images with a clear carrier, which is eitherthermally or photon curable, this technique prints the image with asolvent or a solution, which reacts with pre-coated surface on thesubstrate. For example, the solvent can be water and the agent that ispre-coated on the substrate surface is polyvinyl alcohol (PVA). It iswell known that PVA is dissolvable into water. In this particular case,image is printed onto the substrate surface with the water through theprinter head. Before the water dries, the CLC pigments are sprayed andbrushed. This principle can be further generalized to create colorfulpictures by screen printing, off-set, Gravure, ink jet, bubble jet,Xerox or laser printing and even in 3-D. In addition, this method isalso suitable for painting. Further generalization of this technologycan yield another method. The object to be painted is first whollypainted with a wet carrier that might be thermally or UV curable. Then,a pattern is printed with a fast drying coating through a printingdevice. The area covered by this coating is no longer sticky to the CLCpigments. However, the remaining area where not covered with suchcoating can still adhere to the CLC pigments. Therefore, image iscreated. This method is then termed as “negative” as compared to theprevious methods. Furthermore, the new printing technologies can begeneralized to the situation where ordinary absorptive CMYB pigments areused instead of the CLC pigments.

Applications of the New Invention

[0060] There are many applications that may be explored using this newprinting technology. A first application is in automobile painting.Using the new painting technology, CLC pigments can be painted flat ontoan automobile body such that a color change occurs when viewing anglechanges.

[0061] A second important application is security printing. CLC pigmentsare printed flat using the new technology to ensure a color changeversus the viewing angle. This characteristic is difficult tocounterfeit. In addition, the security pattern will change when viewedwith circular polarizing filters. Of great interest in this area is theusage of IR CLC pigments which are particularly suitable for machinevision application.

[0062] A third application is in general painting using CLC ormultilayer organic or inorganic reflective pigments as the colorant fordecoration as well as for energy saving. Since the light energy is notabsorbed, but reflected, less energy will be used for air conditioningin a house painted with reflective paint.

[0063] A fourth application is in cosmetics. CLC pigments used as fingernail polish, skin colorants, and eyeshadow offer spectacular effects. Inparticular, binder material applied first to a fingernail, then flakeswhich are rubbed to align them are very effective. Very large flakes ofabout 100 or 150 microns give a striking glitter” effect. One otherexample is the use of such reflective pigments in sunblock. Multilayerflakes with a non-liner pitch may reflect a broad band of wavelengths,and in particular block ultraviolet light in the UVA and UVB bands.Normal sunblock lotion uses organic molecules to absorb the ultravioletlight, but the bandwidth of such molecules is normally too small toeffectively block both the UVA and UVB bands. Pigment materials such aszinc oxide and titanium dioxide are very white, and are not appealing.Broadband reflecting flakes, however, reflect the ultraviolet light andare colorless in the visible spectrum. Such broadband reflecting flakesmay also reflect the infrared light as well and lead to a cooling effectwhen the infrared rays of the sun are reflected from the skin instead ofabsorbed by the skin. Flakes of such broadband ultraviolet and infraredreflecting characteristics and visible transmitting characteristics areanticipated by the inventors.

[0064] The methods noted above are examples which may be generalized byone of skill in the art to provide many additional embodiments which areanticipated by the inventors.

[0065] Obviously, many modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, withing the scope of the appended claims, theinvention may be practiced otherwise then as specifically described.

We claim:
 1. A method of producing a light reflective coating on asurface of a substrate, comprising: a) applying flakes of dry nonmetallic reflective material to the surface so that the flakes liesubstantially parallel with the surface, wherein the non metallic flakeshave a mean index of refraction.
 2. The method of claim 1, wherein thestep of applying flakes to the surface comprises: i) applying the flakesof dry non metallic reflective material to the surface; and ii)mechanically working the surface to align the flakes parallel with thesurface.
 3. The method of claim 1, wherein the step of applying flakesto the surface comprises: i) applying an electrical charge on the flakesof dry non metallic reflective material; and i) attracting the flakes tothe surface using an electrical field substantially perpendicular to thesurface, whereby the flakes strike the surface and align parallel withthe surface.
 4. The method of claim 1, further comprising a step ofcovering the flakes with a protective layer.
 5. The method of claim 4,wherein the protective layer has an index of refraction which matchesthe mean index of refraction of the flakes.
 6. The method of claim 1,where the flakes are interference reflectors.
 7. The method of claim 6,wherein the flakes are flakes of CLC material.
 8. The method of claim 7,wherein the flakes of CLC material have a non linear pitch distributionso that the flakes reflect a broad band of light.
 9. The method of claim6, wherein the flakes are flakes of multilayer polymeric material. 10.The method of claim 9, wherein the flakes are flakes of multilayerpolymeric material, where the multilayer polymeric material has a nonlinear pitch distribution.
 11. The method of claim 6, wherein the flakesare flakes of multilayer inorganic material.
 12. The method of claim 11,wherein the flakes of multilayer inorganic material have a non linearpitch distribution so that the flakes reflect a broad band of light. 13.A method of producing a light reflective coating on a surface of asubstrate, comprising: a) applying a coat of binder material to thesurface; and then b) applying flakes of dry non metallic reflectivematerial to the surface, the non metallic reflective flakes having amean index of refraction.
 14. The method of claim 13, furthercomprising; c) mechanically working the surface to align the flakesparallel with the surface.
 15. The method of claim 14, wherein the stepc) is a step of rolling the surface.
 16. The method of claim 14, whereinthe step c) is a step of buffing the surface.
 17. The method of claim14, where the substrate is a fingernail, and where the non metallicreflective flakes are interference reflectors.
 18. The method of claim14, where the substrate is an automobile body, and where the nonmetallic reflective flakes are interference reflectors.
 19. The methodof claim 13, wherein the step of applying the flakes to the surfaceemploys flakes having electrical charges on the surfaces of the flakes.20. The method of claim 13, wherein the step of applying the bindermaterial to the surface is a step where the binder material is appliedin a pattern, and where the flakes adhere to the surface only where thebinder material is applied to the surface.
 21. The method of claim 20,wherein the step of applying the binder material to the surface isperformed using an ink jet printer.
 22. The method of claim 20, whereinthe step of applying the binder material to the surface is performedusing a screen printer.
 23. The method of claim 20, wherein the step ofapplying the binder material to the surface is performed using an offsetpress.
 24. The method of claim 20, wherein the step of applying thebinder material to the surface is performed using xerographic printer.25. The method of claim 13, wherein the binder material is a fluidmaterial.
 26. The method of claim 13, wherein the binder material is afusible material.
 27. The method of claim 13, wherein the bindermaterial is a radiation curable material.
 28. The method of claim 13,wherein the binder material is a thermally curable material.
 29. Themethod of claim 13, wherein the binder material is a contains a volatilesolvent.
 30. The method of claim 13, wherein the flakes are interferencereflectors .
 31. The method of claim 30, where the flakes are flakes ofCLC material
 32. The method of claim 30, wherein the flakes of CLCmaterial have a non linear pitch distribution so that the flakes reflecta broad band of light.
 33. The method of claim 30, wherein the flakesare flakes of multilayer polymeric material.
 34. The method of claim 33,wherein the flakes are flakes of multilayer polymeric material, wherethe multilayer polymeric material has a non linear pitch distribution.35. The method of claim 30, wherein the flakes are flakes of multilayerinorganic material.
 36. The method of claim 35, wherein the flakes ofmultilayer inorganic material have a non linear pitch distribution sothat the flakes reflect a broad band of light.
 37. The method of claim13, wherein the binder layer has an index of refraction which matchesthe mean index of refraction of the flakes.
 38. An object having asurface, comprising: a first layer of a large plurality of dry nonmetallic reflective flakes, the non metallic reflective flakes lyingsubstantially parallel with the surface and substantially coplaner witheach other, the non metallic light reflective flakes having a mean indexof refraction; and a second layer of a binder material in contact withthe first layer and with the surface.
 39. The object of claim 38,wherein the flakes are closely adjacent the surface of the object andwherein the binder material is adherent to the surface of the object andcovers the flakes.
 40. The object of claim 39, further comprising aprotective third layer covering the first and second layers.
 41. Theobject of claim 40, wherein the protective layer has an index ofrefraction which matches the mean index of refraction of the flakes. 42.The object of claim 38, wherein the binder material is adherent to thesurface of the object, and wherein the flakes are separated from thesurface by the binder material and adherent to the binder material. 43.The object of claim 42, further comprising a protective third layercovering the first and second layers
 44. The object of claim 43, whereinthe protective third layer has an index of refraction which matches themean index of refraction of the flakes
 45. The object of claim 38,wherein object is a part of an automobile body.
 46. The object of claim38, wherein object is a sheet.
 47. The sheet of claim 46, wherein theflakes form a pattern.
 48. The object of claim 38, wherein the flakesare flakes of CLC material.
 49. The object of claim 48, wherein theflakes of CLC material have a non linear pitch distribution so that theflakes reflect a broad band of light.
 50. The object of claim 38,wherein the flakes are flakes of multilayer polymeric material.
 51. Theobject of claim 50, wherein the flakes are flakes of multilayerpolymeric material, where the multilayer polymeric material has a nonlinear pitch distribution.
 52. The object of claim 38, wherein theflakes are flakes of multilayer inorganic material.
 53. The object ofclaim 52, wherein the flakes of multilayer inorganic material have a nonlinear pitch distribution so that the flakes reflect a broad band oflight.
 54. The object of claim 38, wherein the binder material has anindex of refraction which matches the mean index of refraction of theflakes.